A SpaceX Falcon 9 rocket ignited a plume of vaporized metal as it re-entered the atmosphere, raising concerns about atmospheric pollution across Europe. This type of contamination is expected to surge as the number of spacecraft and satellites continues to grow.

The Falcon 9’s upper stage, intended for recovery in the Pacific Ocean, suffered an engine failure that led to its uncontrolled descent over the North Atlantic on February 19, 2025.

Witnesses throughout Europe observed fiery debris streaking across the sky, with some fragments landing behind warehouses in Poland. Researchers from Germany’s Leibniz Institute for Atmospheric Physics employed lidar technology to monitor the atmosphere. They noted a tenfold increase in lithium concentration— a significant component of the rocket’s structure— twenty hours after the re-entry event.

Using atmospheric models, researchers concluded that the lithium plume drifted approximately 1,600 kilometers from the re-entry site. This investigation represents the first instance of tracking high-altitude contamination resulting from a specific spacecraft re-entry.

According to Wing, small metal particles could catalyze ozone depletion, create clouds in the stratosphere and mesosphere, and interfere with sunlight’s passage through the atmosphere. “However, this field remains largely underexplored.”

As commercial space launches surge and companies expand their satellite constellations, such as SpaceX’s Starlink and Amazon’s Kuiper, concerns regarding contamination are becoming more pronounced. Currently, around 14,500 satellites orbit Earth, and SpaceX recently applied to deploy an additional 1 million satellites to support Elon Musk’s vision of creating orbiting data centers for artificial intelligence.

To mitigate a potential cycle of collisions that could generate more space debris, satellites are often permitted to deorbit and burn up at the end of their operational lives. Experts warn that space debris could increase by fiftyfold over the next decade, potentially contributing to more than 40% of the mass currently entering the atmosphere from meteorites.

There is a common misconception that space debris simply burns up and disappears in the atmosphere. According to Daniel Cizzo of Purdue University, who did not partake in this study, “We need to be cautious and thoroughly analyze the potential impacts of this material.”

The Falcon 9’s plume is estimated to contain around 30 kilograms of lithium. However, given the alloy composition of the rocket’s hull, it likely contained significantly more aluminum.

When evaporated aluminum interacts with atmospheric oxygen, it forms aluminum oxide particles, which serve as surfaces for chlorine compounds to decompose more easily. The chlorine radicals generated through this process react with and deplete ozone molecules in the stratosphere.

Researchers estimate that the burnout of spacecraft releases approximately 1,000 tons of aluminum oxide into the atmosphere annually, a figure that continues to rise. This exacerbation could extend the ozone hole in the Southern Hemisphere, which has been shrinking as nations phase out ozone-depleting gases. The loss of ozone allows more harmful ultraviolet rays to penetrate, increasing the risk of skin cancer.

“In terms of metals, we are entering a new paradigm where anthropogenic pollution increasingly influences the upper atmosphere, overshadowing natural sources,” says Eloise Marais from University College London. “Space debris risks reversing the progress made in healing the ozone hole.”

Metal oxide particles also function as nuclei for water vapor to coalesce into droplets, potentially leading to the formation of cirrus clouds that trap heat in the upper troposphere.

Scientists have detected particles from a burned-out spacecraft within cirrus clouds. While the effect on global warming is currently considered minor compared to greenhouse gases like carbon dioxide, it could still pose increased risks.

“Substantial evidence indicates that this substance may adversely affect the atmosphere. It is now our responsibility as scientists to assess whether these effects are occurring and the degree of their negativity,” Cizzo stated.

Potential solutions include constructing satellites from wood-like materials—though these may emit black carbon soot upon re-entry—or relocating satellites to high-altitude “graveyard orbits.”

“You must take a moment to consider your intentions before proceeding,” Wing advises. “This rapid growth in satellite launches poses questions that remain unanswered.”